Relay



June 30, 1953 l 1 0, HRUBY, JR 2,644,118

RELAY Filed Jan. 29, 1951 ATTORNEK Patented June 30, 1953 UNITI-:o s STAT Es PATENT for-Fics RELAY John 0. I-Iruby, Jr., Burbank, Calif., .'assignor to Hydraulic .Research and llianufacturing Comrpany, Burbank, ..0alif., a corporation of California l Application Januaryi), 1951,'Serial No.'208',302

(Cl. S17- 131) 2 fpClaims.

The invention relates lto a relay having a solenoid and core for operating anarmature which controls an electric circuit.

The solenoid -is a coil of wire having a resistance which Varies with its temperature. When such a relay is employed in an airplane or other situation having a wide temperature range such as 20G-deg. F., the operation of the relay is erratic.

`Also a fluctuation in the operation of the relay is caused by a variation in thev voltage of the battery which energizes the solenoid.

An object of the inventio-n is to overcomeeach of the above objections. These objects are accomplished by providing a relay having an armature controlled by two substantially identical coils arranged in magnetic opposition. When the flux is thus balanced, with a resultant value of substantially zero, the armature is urged to one of its positions by a spring. The flux balance is upset by reducing the current through one of the coils, to give the resultant flux a finite value suicient to overcome the spring and move the armature to its alternate position. As the coils are equal and opposite, any change in resistance due to a temperature change equally affects both coils but in opposition whereby the flux balance is not disturbed by such temperature change.

Preferably also the equal and opposite coils are connected in parallel to the battery or other source of voltage. As the coils produce fluxes in opposition, any change in current due to fluctuation of the battery voltage, affects both coils equally and does not disturb the flux balance.

The amount of current flowing through both coils, of course depends on the voltage of the battery and the resistance of the coils. However, the magnetic pull on the armature is so large in proportion to the tension of the spring on the armature that a positive action of the armature is assured for Voltage or resistance changes within the working range.

For further details of the invention, reference may be made to the drawings wherein- Fig. 1 is a side view in elevation of a relay according to the present invention.

Fig. 2 is a plan view of the relay of Fig. 1.

Fig. 3 is an end view in elevation of the relay of Figs. 1 and 2.

Fig. 4 is a schematic wiring diagram for the relay in the other figures.

Referring in detail to the drawings, the relay I has a suitable base 2 on which is mounted an inverted U-shaped magnetic core 3 having opposite limbs 4 and 5 which terminate in spaced pole faces 6 and I respectively. In the gap be- 2 tween the pole faces 6 and is an armature 8 having apivotal support as indicated at 9. The armature 8 isurged away from the pole v.faces '6 and 1 by a tension spring I0 having one end thereofengaged with the outer end of armature 8 as indicated at II, the other end thereof being suitably xed to base 2 as indicated at I2. vT'he terminal I3 serves lasa stop for the armature 8 and is arranged at one side thereof, another terminal I4 being arranged at the other side of the armature. The terminal I5 is connected thro-ugh a flexible conductor |6 to the armature 8. The circuit to be controlled is connected tothe terminal l5, and `either to the terminal I3 or terminal. I4 as desired.

On the limb 4 is arranged a coil 20 and on the limb 5 is a coil 2|, the coils 20 and 2| being substantially identical, that is having the same number of turns, the same size of wire and both wound in the same direction so that they are in magnetic opposition on the core 3. This wire may be copper, nickel, chromium or alloy having an enamel coating. Hence both of the pole faces 6 and 1 will either be of north polarity or of south polarity,

" it matters not which polarity is used, the armature 8 fbeing of soft iron and not polarized.

As shown in Fig. 4, the lower terminals of both coils 20 and 2| are connected by conductor 22 to one side of battery or other source 23. The other terminal of coil 2| is connected by conductor 24 to the other terminal 25 of the battery 23 and the corresponding terminal of coil 2| is connected to a switch 26 which illustrates two Ways for upsetting the flux balance of coils 2l) and 2|. With switch 26 in the position shown, the resistance of rheostat 21 may be increased to reduce the current in coil 2B to upset the flux balance and operate armature 8 against the action of spring I0 alternatively, the switch 26 may be shifted to contact 28, whereby switch 29 may be opened as shown to similarly reduce the current in coil 20 and operate armature The armature 8 thus is operated either by operating switch 29 or by shifting the sliding contact 30 of the rheostat 21.

The flux balance of coils 20 and 2| is not disturbed by a change in the resistance of these coils due to a temperature change, or by fluctuations in the voltage of battery 23.

When the relay having the magnetic structure and coils as shown, but with the coils connected in the conventional manner to have the same polarity, the armature pulls in at 61/2 volts and drops out at 3 volts, requiring a voltage difference of 31/2 volts to operate the relay. The sensitivity of the relay is increased according to the present invention, as shown `by the following: With the xed coil 2l at 5 volts, the relay will be balanced if coil 20 has 5 volts applied to it. The relay will operate if the voltage of coil 2B is increased to 7.2 volts and will drop out at 6.6 Volts. Also the relay will operate if the volta-ge of coil 20 is decreased to 2.4 volts and will drop out at 3.2 volts. From this data it is seen that the relay may be operated by upsetting the flux balance in either one of two ways, namely, by making the flux strength of coil 20 either greater or less than the uX strength of coil 2 I.

Various modifications may be made in the invention without departing from the spirit of the following claims.

claim:

1. A relay comprising a U-shaped magnetic core having opposite legs, a winding on one of said legs and a substantially identical winding in magnetic opposition on the other of said legs, said windings having substantially the same temperature coefficient, an armature having opposite ends and an intermediate pivot at one side of said core, one end of said armature having a magnetic portion bridging the ends of said legs, the other end of said armature having a contact, spring means connected to said armature and biasing said armature to one position, a source of current, a circuit connecting one of said windings in shunt to said source, another circuit connecting said other winding in shunt to said source, said other circuit comprising a switch and connections controlled thereby for changing the current in said other winding from a value suflicient to overcome said springto a value insuiiicient to overcome said spring, whereby the operation of said armature is substantially independent of temperature variation of said windings and Voltage fluctuation of said source of current.

2. A relay comprising a magnetic core having two substantially identical windings in magnetic opposition on said core, said windings having substantially the same temperature coefficient, an armature for said core, said armature having a contact, a spring biasing said armature to one position, a battery, a circuit connecting one of said windings across said battery, another circuit connecting said other winding across said battery, said other circuit comprising a switch and connections controlled thereby for changing the current in said other winding from a value sufficient to overcome said spring to a value insufficient to overcome said spring, the magnetic opposition of one of said windings to the other of said windings being substantially independent of wide variation of temperature and of voltage iiuctuation of said battery.

JOHN O. HRUBY, JR.

References Cited in the le of this patent UNITED STATES PATENTS Number 

